﻿/**
* jCache - A client cache plugin for jQuery
* Should come in handy when data needs to be cached in client to improve performance.
* Author: 	Phan Van An 
*			phoenixheart@gmail.com
*			http://www.skidvn.com
* License : Read jQuery's license

Usage:
1. 	Include this plugin into your web document after jQuery:
<script type="text/javascript" src="js/jquery.jcache.js"></script>
2.	[OPTIONAL] Set the max cached item number, for example 20
$.jCache.maxSize = 20; 
3. 	Start playing around with it:
- Put an item into cache: $.jCache.setItem(theKey, the Value);
- Retrieve an item from cache: var theValue = $.jCache.getItem(theKey);
- ...
*/
(function(jQuery) {
    this.version = '(beta)(0.0.1)';

    /**
    * The maximum items this cache should hold. 
    * If the cache is going to be overload, oldest item will be deleted (FIFO).
    * Since the cached object is retained inside browser's state, 
    * a too big value on a too big web apps may affect system memory.
    * Default is 10.
    */
    this.maxSize = 1000;

    /**
    * An array to keep track of the cache keys
    */
    this.keys = new Array();

    /**
    * Number of currently cached items
    */
    this.cache_length = 0;

    /**
    * An associated array to contain the cached items
    */
    this.items = new Array();

    /*
    * @desc	Puts an item into the cache
    *
    * @param	string Key of the item
    * @param 	string Value of the item
    * @return	string Value of the item
    */
    this.setItem = function(pKey, pValue) {
        if (typeof (pValue) != 'undefined') {
            if (typeof (this.items[pKey]) == 'undefined') {
                this.cache_length++;
            }

            this.keys.push(pKey);
            this.items[pKey] = pValue;

            if (this.cache_length > this.maxSize) {
                this.removeOldestItem();
            }
        }

        return pValue;
    }

    /*
    * @desc	Removes an item from the cache using its key
    * @param 	string Key of the item
    */
    this.removeItem = function(pKey) {
        var tmp;
        if (typeof (this.items[pKey]) != 'undefined') {
            this.cache_length--;
            var tmp = this.items[pKey];
            delete this.items[pKey];
        }

        return tmp;
    }

    /*
    * @desc 	Retrieves an item from the cache by its key
    *
    * @param 	string Key of the item
    * @return	string Value of the item
    */
    this.getItem = function(pKey) {
        return this.items[pKey];
    }

    /*
    * @desc	Indicates if the cache has an item specified by its key
    * @param 	string Key of the item
    * @return 	boolean TRUE or FALSE
    */
    this.hasItem = function(pKey) {
        return typeof (this.items[pKey]) != 'undefined';
    }

    /**
    * @desc	Removes the oldest cached item from the cache
    */
    this.removeOldestItem = function() {
        this.removeItem(this.keys.shift());
    }

    /**
    * @desc	Clears the cache
    * @return	Number of items cleared
    */
    this.clear = function() {
        var tmp = this.cache_length;
        this.keys = new Array();
        this.cache_length = 0;
        this.items = new Array();
        return tmp;
    }

    jQuery.jCache = this;
    return jQuery;
})(jQuery);